Spring



Feb. 5, 1952 R'G, PETY 2,584,612

v SPRING Filed May 4, 1945 Ir'trlD BMI i) some .suitable .abrasive @such :as pumice. :plate 'is then secured infa-suitab1e clamp ;such

terial. -at -right-:angles to the-.-p`lane::thereof torremove Patented Feb. 5, 1952 Raymond G. Piety, Tuckahoe,`fN. "Y.,.-assignor `to :Phillps'Petroleum Company, .a corporationaof ,melai/ware .'4 Claims.

..This invention -relates 4tofa specialized aform of pl'il'lg- .Another object jof-this 'invention' is *to -produce 'afiatgspring 'of specialized construction I of ;gen-

l'in connect-ien with the attached drawing.

'intermediate stage in iits processing Figure *2 -is 4`anend -elevational -diagrammatic view of the spring -at la Vmor-e E'advanced stage in itsfprocessing :and

'Figure '3 `is a `*diagria-mrnatic illustration of va still E*inore advanced process -andthe stage .diagram-matically illustrati-ng the ethingfs'tep.

The subject matter iof thi-s 'I invention rarosef by reason of the dfficulty lpresented in cuttingl a fiat -spring of intricate config-uration and accurate idimensions such asflwill 'be fdescri'bedfbelow inconnection with the attached drawing, from a--sheet .of .suitable resi'lient materialstiitl'iout creating -stresses therein. "'IYheconfiguration-of Athe finished spring is illustrated in outline 'in'FigurefL and vcomprises the :areas =within'.thefourved lines Il. Thus it is a fiatfisprng'having rigidity in the planethereof and -theproper fiexibility at right angles to the'plane thereof. The spring is made of any suitable resilientmateriay-but for a parfticular purpose is *preferably ;made from: asheet Ill of-beryllium copper of thezjhmperffthickness. The large..cential.nirclappoition..and the rectangular portion surrounding the lines Il represent *the waste so that r'thespring consists of 3threespirally arranged arms integrally connected.

In making this spring infaccordanceWiththis invention a .sheet Hiv of .suitablespringrmaterial such "as beryllium copper is wthoroughly washed 'to remove all 4grease andrfureign material from both -surfaces thereof after :itgiis cleaned with :The

as is illustrated.Figuetfimprising several spring arms `l`6 which can clip over the edge of theplate. The exact form cfthe clamp i-simma- The wet plate isi-then ;whirled watean ::axis

as much water as possible, although 'thei'plate -nee'dnotfnecessarily'becompletely'dry. 'The-plate still 'in the clamp fis i then ydippe'd vin a -f-suitable lightesensitive coating which ultimatelyformsfan etching resist after processing. .Such `a "light sensitive coating forms vno part of *this inven- 'tionsince there area number of themfcommercially available and suitable for ``the' purpose 'having extensive use in the photo-etching art. ``The fccated lplate is vthen whirled as lbefore, While maintaining the plate in ahorizontal position so as 'to 'uniformly 'distribute -the coatinginan veven layer on'bothsides thereof. It isfthen dried -in a blast of warm air from any'suitable source, preferably while lstill revolvingpn theaxis of :the supporting clamp.

'I-n dippingthe plate i. ill to coatfitit is preferable to have two ftrays ;of ncoating -material -so that `any dilution resulting from :the moisture on the plate occurs in the first tray. Dippingfthe kplate -in.:the vi-secon'd htray of sensitized 'coating material insures thatthe coating Will :have Vits '-f-ul-l light 'sensitivity. The coating vis Vdried by -warm air'at a'temperature, for example-of about ^*C. for about -tenfminutes The Vdryingtem- Aperatureand-.time Wi11,of-.course,fvary with the -particular lsensitized coating used. The dried plate isnow ready for exposure :and Ypreferably :shoul'dfbe exposed at once, although ifmaintaned 'in -a "dark dry .placerit wi1l;remain sensitive for at least .thirtyminutes 'A portion of thecoating :for vone side .of .the plateis-shown at 12 vin Figure 1, it being vunderstood :that 'the Ventire surfacefof `@both :sides of :the plate 'will vbe-thus ooated.

.'-A 'pair` of templets '123 ;and Ill previously pre- :paredflare connected in ftheform :of la book by Jmeans vof ..a "flexible hinge l' o'f any *suitable material. The templets I 3.;andi4 :are made of -any;-.s-uitaible transparent;materialgsuch -as gglass, clear scelluloid, cellulose .acetate zand the like, :and :there is :drawn thereon mirror images ;of .ithespring :bymeaznsrof heavy blacklines vofinl: for some other suitable-"marking material. The

' .lines :on ;the itemplets Will -rhave ;exactlythe ap- .pearanceand ;shapezof-.jthefilinesll of Figure -1 ;which inclndethc ;small Circular :dots which -de- `fine Z'the areas fiwhich Will become ;holes the ends of th-e arms ;of the jfinished spring. Mir- :Irror ;images :of the springs are 'drawn ;on the --iemnets 13 and .ttf-sdthatwhen ,the plate HI Yisff-'alaced b etwcen them, as; igllustrated. ;in Eigure ;end *the rftemplets ;Is ;and ::l-4 .closed on :the 4 xldes :of st-he ;plate 'rin like a ebook vthe ;Pairs -Lof :mtlines ni the spring :are eXaetl-y :algned :in ia transierse sense.

heat filters such as cells containing the copper sulphate solution with the filter placed close to the printing frame. The preparation :of the plate and the exposure thereof may be carried out in a normally lighted room if not delayed too long. At this point it may be well to note that if desired only a single templet could be employed and the plate successively exposed on both sides.

The exposed plate is ready for developing as soon as exposure is complete. Any suitable developing solution may be employed compat-l ible with the particular coating used, all in accordance with knowledge in this art. After development in a suitable solution the plate is removed therefrom and rinsed in running water, during which time it is gently rubbed with absorbent cotton. The result of this treatment is that those portions of the coatings masked by the black lines on the templets are removed, exposing the metal of the plate lu in a configuration represented by the lines and black dots H. VThe plate is then slowly baked, preferably for three or more hours at 150 C., or thirty to forty-five minutes at 170 C. This converts the remaining portions of the coatings 12 to the well known enamel resist used in the etching art.

The plate is now ready for the etching operation. It is replaced in the clamp [6 and mounted on the shaft l'l of a suitable motor 18 so that it will be revolved on an axis at right angles to the plane of the motor. The motor 18 is positioned so that the plate is immersed in the etching solution 23 in a suitable container IQ. The etching solution is the usual copper sulfate-sulfuric acid bath. Immersed in the solution is a cathode 20 preferably of copper positioned parallel to the plate Ill. A suitable current source, not shown, is connected to the leads 2! and 22, which in turn are respectively connected to the cathode 20 and the motor frame or motor shaft ll by the lead 22.

The motor IS is preferably a slow speed motor so that the plate I!! revolves slowly as etching progresses. This rotation of the plate tends to prevent polarization.

For the sake of completeness the etching solution may comprise 28 ounces of copper sulfate and 3 to 5 fluid ounces of sulfuric acid to one gallon of water. The voltage of the current source may be of the order of 4 to 6 volts. In one commercial operation it took about ten minutes to complete the etching operation although, of course, the etching period is subject to several variables, as is well known in the art, including, of course, the thickness of the plate. Since the only portion of the plate which is exposed are the lines and dots Il which are 'aligned on both sides of the plate, it is clear as explained above since etching from both sides of the plate reduces undercutting of the metal.

When the etching is completed the plate 10 separates into three parts comprising the central Circular portion, the spring itself, and the rectangular fringe surrounding the spring. The first and third portions are, of course, waste in so far as this operation is concerned. The resulting spring is then treated with a resist enamel remover Which will vary with the material of the coating, so as to clean up the final spring.

By this procedure the spring which is etched or cut out of the plate has very clean edges and needs no filing.

There are, of course, many variations that may be employed in this process without departing from the novel method of producing a flat spring as herein disclosed, as those skilled in the art will appreciate. For example, the plate l0 may be large enough so that several springs are etched at the Sametime. Likewise, a pair of cathodes 20 can be positicned lat opposite sides of the plate to increase the efliciency of the etching operation. As already indicated'various forms and types of resists are available and for that reason no specific resist developer and cleaning solutions are named since they are not critical in this process.

I do not, therefore, desire to be strictly limited to the details of the disclosure herein given, but only as required by the scope of the appended claims.

What is claimed is: A

1. A flat spring having rigidity in the plane thereof and flexibility at right angles to the plane thereof, said spring consisting of a single uniform sheet of fiat spring metal having a central opening therein and a plurality of flat spiral arms of substantially uniform width in the plane thereof,

veach arm extending from a point contiguous to said central opening in an arc substantially concentric to said opening for a total distance of about one-third of the circumference of said spring, each arm being free .at its outer end;

2. In the spring in accordance with claim 1 the central opening of the spring being defined by a border substantially as Wide as the arms of the spring.

3. In the spring in accordance with claim' 2, the terminal ends of the spring arms having apertures therein.

4. The spring in accordance with clain 3 formed from beryllium copper,

RAYMOND G. PIETY.

REFERENCES CITED The pfollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,826,415 Bragg et al. Oct. 6, 1931 1,883,249 Spencer Oct. 18,'1932 1,975,114 Masing Oct. 2, 1934 2,169,787 Becker Aug. 15, 1939 2,308,695 Johnson Jan. 19, 1943 2,348,225 Petty May 9, 1944 2,375,613 Betcheller May 8, 1945 2,407,757 MacCallum Sept. 17, 1946 FOREIGN PATENTS Number Country Date 161,910 Switzerland May 31, 1933 446,783 Great Britain May 6, 1936 

